The field of the present invention is flashlights.
Flashlights are frequently designed for rugged use. However, in spite of the overall rugged nature of devices so designed, each, by their very nature, employs a light bulb. The bulbs used vary in construction; but all use a thin filament as a means for physically generating light. In spite of all possible mounting means for such filaments or for the bulb itself, the filaments are subject to being broken by shock loading. This has been observed even without damage to the flashlight itself. Therefore, the filament typically is the most fragile element in such ruggedly designed flashlights. Furthermore, filaments have been found more susceptible to breakage when hot, i.e., when the flashlight is on.
To mitigate the difficulties associated with the fragile nature of bulb filaments, flashlights have been equipped with spare bulbs. As a spare bulb may be more resiliently mounted and remain in a cold state, it is far less likely to be damaged or broken than a bulb in use. One such design is found in U.S. Pat. No. 4,286,311, the disclosure of which is incorporated herein by reference. The tail cap is hollowed out to receive an extra bulb sandwiched between two pads of sponge rubber or the like. This is indicated to be for the purpose of preventing breakage of the spare bulb in the event the flashlight should be dropped or struck a heavy blow. Another such arrangement is illustrated in U.S. Pat. No. 4,527,223, the disclosure of which is incorporated herein by reference. Again, a spare bulb is accommodated within a tail cap assembly where it is protected by a piece of resilient material. A spare bulb is housed within a tail-cap between two pads in U.S. Pat. No. 4,388,673, the disclosure of which is incorporated herein by reference. In U.S. Pat. No. 4,577,263, a miniature bulb having contact pins rather than a plug is located within a bore in a tail cap assembly, the disclosure of which is also incorporated herein by reference.
Of particular interest are flashlights such as certain of those disclosed in the aforementioned patents which are used by emergency services such as police and fire departments. These flashlights must be rugged and very reliable.. Such users place themselves in harms way which, by definition, includes very adverse environmental conditions and shock loadings. Having an available, undamaged spare bulb could mean the difference between life and death.
In providing for a protective spare bulb mounting, it is advantageous to provide against shock loading and provide for fixed but resilient placement and easy access. Additionally, it is advantageous to create a mounting which admits of easy assembly while assuring secure retention of the bulb. Further, for replacement by users of such flashlights, it is advantageous to have a specific mounting position such that a replacement spare bulb may be positioned appropriately and securely with relative ease.
Users are unlikely to check the-spare bulb until needed. Insuring a proper positioning and secure yet resilient retention of the bulb creates flashlight reliability desired for a true emergency device.